B60C23/001—Devices for manually or automatically controlling or distributing tyre pressure whilst the vehicle is moving

B60C23/003—Devices for manually or automatically controlling or distributing tyre pressure whilst the vehicle is moving comprising rotational joints between vehicle-mounted pressure sources and the tyres

Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

Description

The invention relates to a device according to the
Features of the preamble of claim 1. The invention
further relates to a method of pressure adjustment
according to the features of the preamble of claim 13.

FR-A-1 247 604 shows the features of the preamble of
Claim 1; the features of claim 13 are from US-A-5 674 332
known.

Devices and methods for adjusting the tire pressure
are used in particular in agriculture to
agricultural vehicles such as tractors
to be able to adapt the respective operating conditions. With
increasing performance of agricultural vehicles
these are developed for ever larger total weights.
To the resulting soil compaction with their
To reduce unwanted side effects can be at the
Vehicle devices for adjusting the tire pressure
be provided, for example, the tire pressure at the
Reduce field work compared to road pressure.

EP-B1-0 164 917 shows a central tire inflation system
with control means and a wheel valve arrangement. The
Control means provide an input pressure for a first one
Connection of a pressure relief valve ready. The pressure relief valve
contains a second devoted to the atmosphere
opening connection and a third connection, which has a
Connection line and a rotating union with a
is connected to rotating tire valve assembly. The first
Connection and the third connection of the pressure relief valve
are connected when the inlet pressure is the pressure at the third
Connection exceeds. The third connection is with the
Vent port connected when the pressure at the third
Connection exceeds the inlet pressure. The wheel valve assembly
is connected to an inflatable tire. she
allows a flow when at their entrance side
Pressure is present that exceeds a first reference pressure and
if the pressure in the tire is above a minimum
Wheel reference pressure is. The tire is vented
via the pressure relief valve in front of the rotating union.
To do this, the system must be vented
be applied so that the wheel valve assembly their
in the open position. This venting pressure acts
actual ventilation of the pressure chamber counter to what the
Bleeding process hindered. In addition, the
Vent port located far from the pressure chamber
slowing down and hindering the venting process.

DE-OS-38 36 105 shows a tire pressure control system for
all-terrain motor vehicles consisting of a stationary
Valve combination, one rotating union for one wheel
Compressed air supply line and for a control line and
one co-rotating valve combination per wheel. The stationary
Valve combination includes a relay valve, at least one
Pilot valve and a closing pressure control valve. The co-rotating
Valve combination includes a wheel control valve
which is caused by a pressure pulse on the supply line
opened and by the control pressure on the control line
is closed, and an upstream of this
Quick release valve, which is used to blow off the tire air
responsible is. The blow-off opening of the quick release valve can be a
Check valve must be connected downstream. In this embodiment
both the control line and the supply line
by means of a rotating union with the wheel control valve
get connected. This is complex and expensive.

FR-A-1,247,604 discloses a tire inflation system
that the pressure in the tires of a vehicle individually or
can be changed together. The system includes one
Pressure source, manual control, a pressure gauge and
several valves and lines, the tire one each
Slider valve is assigned that is closed when in the
System no or a low pressure is present, over which the
Tire is connected to the pressure source when a first,
higher pressure is applied and via which the tire is deflated,
if there is a second pressure in the system that is the first
Pressure exceeds.

US-A-5,647,927 shows a central tire inflation system
with a digital computer that has optimal air pressure for
the tires of a vehicle, for example, to minimize the
Fuel consumption and tire wear determined and on
an air supply system transmits an output signal to
adjust the tire pressure to this optimal tire pressure.

The problem to be solved by the invention is in the
complicated structure of the known tire inflation systems and
seen the time-consuming venting.

The problem is solved by the teaching of the invention
Claims 1 and 13 solved. More beneficial
Refinements and developments of the invention are based on
Sub-claims emerge.

The inventive device for adjusting the pressure in
at least one tire of a vehicle includes one
pneumatic control unit, a pressure sensor, a
Rotary union and a rotating wheel valve arrangement with
different positions. The device is with a
Compressed air source connected and the control unit protrudes
a connecting line and the rotating union with the
Wheel valve arrangement, the respective position of the pressure level in
depends on the connecting line. The wheel valve assembly
has at least one closed position, one
Flow position and one opening to the ambient air
Vent position. The wheel valve assembly takes theirs
Flow position on, if on in the connecting line
Ventilation pressure is present. She takes her vent position
if there is a pressure in the connecting line that
the ventilation pressure at least by a predetermined value
exceeds, and it assumes its closed position, if in
the connecting line is subject to a closing pressure which is around
at least a predetermined pressure difference value below the
Ventilation pressure. According to the pneumatic one knows
Control unit at least one high pressure valve and one
Has medium pressure valve, which in parallel lines between
the compressed air source and a pressure level line arranged and
each between a blocking position and a flow position
are switchable. In the line of the medium pressure valve
a pressure reducing valve is arranged, which the
Sets ventilation pressure. The one through the pressure reducing valve
The pressure set is greater than the maximum required
Ventilation pressure of the tires, but less than the pressure
which is necessary to move the wheel valve assembly to its venting position
bring to. If the pressure level line with
the connecting line is connected, takes the
Wheel valve assembly their vent position if that
High pressure valve is open. It takes its flow position
on when the medium pressure valve is open and the
Wheel valve arrangement with the through the pressure reducing valve
reduced pressure is loaded.

The ventilation takes place directly on the wheel, which means that the
Venting time is shortened. There only has to be one
Lead through the rotating union, because the
Control of the wheel valve arrangement only by the
Pressure in the connecting line and not through one
additional control line takes place.

The device according to the invention enables rapid
Modification of the limit values when changing tires and the
Taking into account the load. It offers especially then
Advantages if the tire pressure is changed frequently around him
depending on the working conditions of the wheel load and the
current driving speed according to the specifications of the tire manufacturer
optimally and continuously adjustable. The current
Tire pressure limit values can be changed either from
Driver or a suitable one built into the tire
Transponders are updated. The current load of the
Tires can result from the deflection of the vehicle.

The pressure should be adjustable on several tires of the vehicle
these tires are preferably with a common one
stationary pneumatic control unit connected. hereby
the number of components can be reduced. The
pneumatic control unit is preferably a modular
trained valve block.

A preferred development of the device according to the invention
provides that through the stationary pneumatic control unit
not just the pressure of a vehicle's tires, but
also the pressure of one or more tires with the vehicle
connected devices or trailers is adjustable.

It is advantageous to use the pneumatic control unit
to be installed stationary on the vehicle. With this a
The pressure can be adjusted at any time without any
external control system must be started. One at that
Vehicle mounted pneumatic control system can be in
advantageously for setting the pressure with the vehicle
connected trailer or device. When attaching
or when changing trailers, only the respective need
Lines are connected and there are no additional
complex renovation work.

It is advantageous to have the wheel valve arrangement in the form of a
Execute slide valve. The slide valve is in
Dependence on the pressure in the connecting line in his
brought each position. Slider valves are easy in the
Structure and insensitive to flow. They are used frequently
and are therefore inexpensive.

The wheel valve arrangement is advantageously replaced by a
Spring loaded by the action of the wheel valve assembly
counteracts controlling air pressure in the connecting line.
By designing the spring, the switching pressure points can be
of the different valve positions.

The pneumatic control unit advantageously includes
at least one switching valve. This shows one that
Connection line to the venting position opening to the surroundings
on. The changeover valve is in this position
the connecting line is depressurized, which makes it less strong
is claimed. The wheel valve arrangement decreases when depressurized
Connecting line in an advantageous manner their closed position
on, so that no pressure reduction from the tire via the wheel valve arrangement
he follows.

It is convenient if the pneumatic control unit
has at least one switching valve, which between a
Pressure level line of the control unit and the connecting line
lies. The changeover valve is between a vent position
and a flow position switchable. In the
Venting position, the connecting line is vented and
thus relieved. At the same time, the pressure level line
cordoned off so that their pressure is maintained. In the
The connecting line with the
Pressure level connected.

The tires advantageously stand on at least one axle
the vehicle and / or an attached device or one
Trailer each via associated wheel valve arrangements and
Rotary unions with only one assigned to the axis
Connection line in connection. The connecting line is
via an associated changeover valve with a pressure level line
connectable to the pneumatic control unit. The
The pressure in the tires of one axle is set at
common in this embodiment, which in all tires one
Axis the same pressure is set. This is beneficial
because the tires of one axle are usually the same
Are exposed to loads. In addition, the number of
the individual parts forming the pneumatic control unit
reduced.

In order to control and monitor and in particular a
Remote control and monitoring of the device e.g. from
To enable the driver's cab of a vehicle is from
Advantage, the changeover valves and / or the high pressure valve
and / or to design the medium pressure valve as a solenoid valve
and through an electrical or electronic unit too
Taxes.

The changeover valves and / or the high pressure valve and / or the
Medium pressure valve take preferably in the de-energized state
their locked position. For the changeover valves, this corresponds to
Locked position preferably at the same time as the venting position
for the connecting line. This is the
Wheel valve arrangement in the de-energized state in its closed position,
causing the tires in the event of a power failure
not be vented.

Preferably by an electrical or electronic
Unit by a pressure sensor in a pressure level line
processed data processed. This makes it possible for the
electrical or electronic unit one to reach
a preselected or required pressure
or ventilation process automatically.

The electrical or electronic unit can
Wheel valve arrangement in the desired position
Venting and ventilation or brought into the closed position
become. The electrical or electronic unit leaves over it
monitoring and testing of the wheel valve arrangement.
It enables controlled pressure setting and pressure monitoring
several wheel valve arrangements.

The inventive method for adjusting the pressure in
at least one tire preferably uses the
described device according to the invention. To the
Tire valve arrangement briefly becomes a ventilation pressure
applied to the wheel valve assembly in its flow position
bring to. Then the actual pressure value of the tire in the
Connection line measured. From a comparison between the actual pressure value
and a predefinable target pressure value becomes a
Ventilation time determined. Then the ventilation pressure
or the venting pressure to the
Wheel valve assembly applied to aeration or venting
of the tire. The process steps are through
controlled an electronic unit in which an initial,
Predefinable functional relationship between the actual-target difference
and ventilation time or ventilation time saved
is. This gives the flow behavior or the parameters of the
Device again. The functional relationship is under
Taking into account the initial actual-target difference and the
Sum of the individual ventilation times or ventilation times
modified to match the specific circumstances, such as
especially the actual flow characteristics and
Adjust tire parameters. The process steps mentioned
ensure an adaptation of the system to changes in
Flow characteristics and tire parameters. Beyond that
it is possible to change the tire pressure depending on the
Determine road conditions, wheel load and speed
and adjust. This procedure enables accurate and
quick adjustment of tire pressure.

It is advantageous to repeat the above-mentioned manufacturing steps
to be carried out until the actual pressure value is within a predeterminable
Tolerance range lies, whereby an iterative approximation to the
required pressure takes place.

Using the drawing, which is an embodiment of the invention
shows, the invention and further advantages are below
and advantageous developments and refinements of
Invention described and explained in more detail.

It shows:

Fig. 1

the schematic representation of a device according to the invention for a vehicle with four tires and

Fig. 2

a diagram to illustrate a tire pressure adjustment process.

A vehicle, not shown, for example a
Agricultural tractor, is with a device 10 for adjustment
of pressure in his tires 12, 13. The in Fig. 1st
Device 10 shown in more detail contains a pneumatic one
Control unit 22 that with the four tires 12, 13 of the not
shown vehicle is connected via connecting lines 24.
Each tire 12 is assigned a rotary union 26, which
the connecting line 24 with a rotating wheel valve arrangement
28 connects. Each wheel valve assembly 28 protrudes
a connecting line 29 to the inside of the associated tire
12, 13 in connection. The device is with a
Compressed air tank 14 via a supply line 16, in the
an overflow valve 18 is provided. The
Compressed air container 14 is provided by a compressed air source 20
Compressed air supplied. The compressed air source 20 is
for example, a compressor that the air pressure brake system
with the highest priority of the brakes.

The pneumatic control unit 22 is stationary on the vehicle
attached. The coming from the compressed air tank 14
Supply line 16 is divided into control unit 22
two line strands 30, 32, the first strand 30 a
High pressure valve 34 in the form of a spring-loaded solenoid valve
with a closed position 36 and a flow position 38
includes. In the second line 32 there is a medium pressure valve
40 in the form of a second solenoid valve of the same type,
which is preceded by a pressure reducing valve 42. Behind
the high pressure valve 34 and the medium pressure valve 40 are the
two line strands 30, 32 into a pressure level line 25
merged. The pressure level line 25 stands with a
Pressure sensor 44 in connection. About two of the same kind as
changeover valves 46, spring-loaded solenoid valves,
48, which is a vent position 49 and a flow position
38, the pressure level line 25 leads
each one of the connecting lines 24, which is a connection
to the tires 12.

The wheel valve arrangement 28 is in the form of a slide valve
a closed position 54 ', a flow position 54 "and
a vent position 54 '' 'executed. The slider of the
Wheel valve assembly 28 is one end by the action of a
Spring 56 loaded and by this in its closed position 54 '
pressed. On the other hand, the slide is the pressure in one
Control line 58 exposed to the connecting line
24 is connected. According to that by the control unit
22 takes predetermined pressure level in the connecting line 24
the wheel valve arrangement 28 one of its three positions 54 ', 54 ",
54 '' a.

The pneumatic control unit 22 stands with a
electronic unit 60 in connection which the
Changeover valves 46, 48, the medium pressure valve 40, the
High pressure valve 34 controls and the measured values of the pressure sensor
44 evaluates.

In the following, the mode of operation of the shown
Device will be described.

The overflow valve 18 arranged in the supply line 16
opens only when in the compressed air tank 14
predeterminable minimum pressure prevails. This ensures
that only compressed air is then removed from the compressed air container 14
if the pressure is above the minimum pressure to supply a
Air brake system is. To determine if the
Compressed air tank 14 to operate the device
has the necessary operating pressure, can
Open high pressure valve 34. The compressed air tank 14 is
thereby connected to the pressure sensor 44. The pressure sensor 44
delivers the determined data to the electronic unit 60,
to prevent ventilation if none
there is sufficient air pressure.

To ventilate the tires, the medium pressure valve 40 is passed through
the electronic unit 60 in its flow position 38
brought. Furthermore, the switching valve 46 for ventilation
the tire 12 of the front axle 50 or the switching valve 48 for
Ventilation of the tires 13 of the rear axle 52 or both
Switch valves 46, 48 brought into their flow position 38.
Since the pressure reducing valve 42 is located in front of the medium pressure valve 40
is arranged, is in the connecting line 24
reduced compared to the pressure of the compressed air tank 14
Ventilation pressure on. This is via the connecting line 24
and the control line 58 to the spool of the wheel control valve
28 created, the wheel control valve 28 its
Flow position 54 '' and the tires 12, 13 filled
becomes.

In order to deflate the tires 12, 13, the medium pressure valve
40 closed and the switching valve 46 and / or that
Switchover valve 48 into the respective flow position 36
brought. The operating pressure of the air container 14 controls
here the wheel valve assembly 28 directly and brings them in
its venting position 54 '' '. The inside of the tires 12, 13
is vented directly to the atmosphere without the
Venting against a control pressure or over long lines
must be done.

If the tires 12, 13 are neither to be ventilated nor to be vented, then
all solenoid valves 34, 40, 46, 48 are de-energized and
closed with it. The changeover valves 46, 48 open in this
Position the connecting line 24 to the environment, so that on the
Slider of the wheel control valve 28 and there is no pressure
moves to the closed position 54 ', in which the
Connection line 29 is closed.

To check the tire pressure, first a short one
Ventilation process performed to the tire valve assemblies
28 to bring in their flow division 54 ''.
Then the solenoid valve 40 is closed and the
Pressure sensor 44 measures that in the connecting line 24
pressure present, which corresponds to the pressure in the tire 12, 13
equivalent.

Between the ventilation, venting and measuring processes
are the changeover valves 46 and 48 in their
Vent position 49, whereby the connecting line 24 with
is connected to the environment and thus also the area of
Rotary unions 26 is no longer loaded with pressure.

The control of the solenoid valves 34, 40, 46 and 48 in the
pneumatic control unit 22 takes place by means of a
Fig. 2 shown and described below.

At certain points in time, which are specified either by the electronic unit 60 or else manually, for example by the operator of the vehicle, a process for regulating the tire pressure is started. For this purpose, the pressure p 0 is first measured in one or both pairs of tires. For this purpose, the ventilation pressure is briefly applied to the tire valve arrangement 28 (opening of the valves 40 and 46 or 48). The pressure p 0 of the tires 12, 13 in the connecting line 24 is then measured by the pressure sensor 44. Based on the measured tire pressure, the electronic unit 60 determines whether a tire pressure adjustment is necessary. This results from a comparison between the pressure p 0 and a predetermined pressure value p 1 . If the pressure values p 0 , p 1 deviate from one another, then the electronic unit 60 determines a time period t 1 for a necessary ventilation process. The ventilation pressure or ventilation pressure is applied to the wheel valve arrangement 28 by a corresponding control of the solenoid valves 34, 40, 46, 48 for the calculated time period t 1 , so that the tires 12, 13 are ventilated or vented. After the ventilation process has taken place, a second pressure measurement is carried out. If the measured pressure value p m again does not correspond to the predetermined pressure p 1 , the process is repeated. This continues until the selected pressure value p 1 is reached. This method provides an iterative approximation to the pressure value p 1 to be achieved . It can also be provided that the process is terminated when the value reached is within a predetermined pressure tolerance range T or when a certain number of ventilation processes have been carried out. The latter ends the process even if a tire is defective and the preselected pressure p 1 cannot be reached.

The method steps described are controlled by the electronic unit 60, in which an initial, theoretical functional relationship F between the actual-target difference in the pressure in the tires 12, 13 and the necessary ventilation period t 1 , t 2 or ventilation period is stored. This theoretical relationship F is used to set the iterative ventilation time t 1 , t 2 and / or ventilation time. If the tire pressure reaches the pressure tolerance range T, the ventilation process or the ventilation process is ended. The electronic unit 60 now determines an actual functional relationship G from the ventilation times t 1 , t 2 , which is stored and on the basis of which subsequent ventilation processes are carried out. In this way, the process is adapted to the actual flow conditions in the system.

In the exemplary embodiment shown, both are
Tire 12 of the front axle 50 and the two tires 13 on the
Rear axle 52 of the vehicle, not shown, together
driven. However, it is also conceivable for each tire 12, 13
individually or the tires 12, 13 of the entire vehicle
head for together.

In addition, it is possible to also tire one
to include the vehicle coupled trailer in the device.
It is conceivable here the tires of the trailer
for example individually, in pairs or in combination with the
Adjust tires 12 of the vehicle.

Claims (14)

Apparatus for adjusting the pressure in at least one tyre (12, 13) of a vehicle, with a
pneumatic control unit (22), a pressure sensor (44), a rotary feed through (26)
associated with the at least one tyre (12, 13) and with a wheel valve device (28)
rotating with the tyre (12, 13) and which can be positioned in various positions (54',
54", 54"'), wherein the apparatus (10) is connected to a source of compressed air (20)
and the control unit (22) is connected to the wheel valve device (28) by a connecting
line (24) and the rotary feed through (26), the current position (54', 54", 54''') of the
wheel valve device depending on the pressure level in the connecting line (24),
wherein the wheel valve device (28) has at least a closed position (54'), a through-flow
position (54"), in which a connection is created between the control unit (22)
and the at least one tyre (12, 13), as well as a venting position (54"') opening the at
least one tyre (12, 13) to the ambient air, and the wheel valve device (28) assumes its
through-flow position (54") insofar as an inflation pressure is present in the
connecting line (24), assumes its venting position (54''') insofar as a venting pressure
is present in the connecting line (24), exceeding the inflation pressure by at least a
predetermined value, and assumes its closed position insofar as a closing pressure is
present in the connecting line (24), lying by at least a predetermined pressure
difference value below the inflation pressure, characterized in that the pneumatic
control unit (22) comprises at least a high pressure valve (34) and a medium pressure
valve (40), which are arranged in parallel lines (30, 32) between the compressed air
source (20) and a pressure level line (25) connectible to the connecting line (24) and
which can each be switched between a closed position (36) and a through-flow
position (38), and in that a pressure reducing valve (42) is arranged in at least the line
(32) of the medium pressure valve (40) and adjusts the inflation pressure.

Apparatus according to claim 1, characterized in that the pneumatic control unit (22)
is connected to a plurality of tyres (12, 13), wherein an individual rotary feed through
(26) and a wheel valve device (28) are associated with each of these tyres (12, 13).

Apparatus according to either claim 1 or 2, characterized in that the pneumatic
control unit (22) is connected to at least one tyre of an implement or trailer attached
to the vehicle, in order to adjust the pressure in this tyre.

Apparatus according to any of claims 1 to 3, characterized in that the pneumatic
control unit (22) is fitted stationary on the vehicle.

Apparatus according to any of claims 1 to 4, characterized in that the wheel valve
device (28) is in the form of a slide valve which has at least a closed position (54'), a
through-flow position (54") and a venting position (54"').

Apparatus according to any of claims 1 to 5, characterized in that the wheel valve
device comprises at least one spring (56) which acts against the air pressure in the
connecting line (24) and defines the switch-over pressure values for the different
valve positions.

Apparatus according to any of claims 1 to 6, characterized in that the pneumatic
control unit (22) includes at least one switch-over valve (46, 48) which has a venting
position (49) opening the connecting line (24) to the surroundings.

Apparatus according to any of claims 1 to 7, characterized in that the pneumatic
control unit (22) comprises at least one switch-over valve (46, 48) which lies
between the pressure level line (25) of the control unit (22) and the connecting line
(24) and which can be switched between a venting position (49) in which the
connecting line (24) is vented and the pressure level line (25) is blocked, and a
through-flow position (38), in which the connecting line (24) is connected to the
pressure level line (25).

Apparatus according to any of claims 1 to 8, characterized in that the tyres (12, 13)
of at least one axle (50, 52) of the vehicle and/or a towed implement or a trailer are
each connected through associated wheel valve devices (28) and rotary through feeds
(26) to a connecting line (24) associated with the axle and in that the connecting line
(24) can be connected through an associated switch-over valve (46, 48) to a pressure
level line (25) of the pneumatic control unit (22).

Apparatus according to any of claims 1 to 9, characterized in that the switch-over
valves (46, 48) and/or the high pressure valve (34) and/or the medium pressure valve
(40) are in the form of magnet valves, which can be controlled by an electrical or
electronic unit (60).

Apparatus according to claim 10, characterized in that the switch-over valves (46,
48) and/or the high pressure valve (34) and/or the medium pressure valve (40)
assume their blocking position (36) in the no-current state.

Apparatus according to one or more of claims 1 to 11 characterized in that the
pressure sensor (44) is connected to the pressure level line (25) and issues the
detected pressure measurement values to an electrical or electronic unit (60), which
for its part effects control of the valves of the control unit (22) in dependence on the
detected pressure level.

A method of adjusting the pressure in at least one tyre (12, 13) of a vehicle, with an
apparatus according to any of claims 1 to 12, wherein an inflation pressure is applied
briefly to the tyre valve device (28) and the actual pressure value (p0) of the tyre (12,
13) in the connecting line (24) is measured, an inflation duration (t1) or a venting
duration (t2) is then determined from a comparison between the actual pressure value
(p0) and a predeterminable set-point pressure value (p1), and in that the inflation
pressure or the venting pressure is then applied for the determined duration (t1, t2) to
the wheel valve device (28), in order to effect inflation or venting of the tyre (12,
13), characterized in that the method steps are controlled by an electronic unit (60) in
which an initial functional relationship between actual/set-point difference and
inflation duration or venting duration (t1, t2) is stored and in that the functional
relationship is changed in the light of the initial actual/set-point difference and the
sum of the individual inflation durations or venting durations.

A method according to claim 13, characterized in that the method steps set forth in
claim 13 are carried out repetitively until the actual pressure value (po) lies within a
predeterminable tolerance range (T).

EP199909101681998-02-041999-01-30Device and method for adjusting the tire pressure on a vehicle
Expired - LifetimeEP1051302B1
(en)

Tire pressure adjusting device for e.g. tractor, has tire valve arrangement with outlet and filling valves that are passed over to their opened and closed positions when air ducts have respective pressures

Tire pressure control system for wheeled vehicle, has valve device comprising wheel-fixed unit of two-channel sealed passage and non-wheel fixed unit for rotary joint, that form fixed terminals for control line and supply line